


The Lunar Mermaid

by Kiramochis



Category: IDOLiSH7 (Video Game)
Genre: Attempted Murder, Ft a brief appearance by Iori, It's not really relevant but I'm tagging it anyway, M/M, Written for IDOLiSH7 Secret Santa, based on the little mermaid, i7ss20
Language: English
Status: Completed
Published: 2020-12-26
Updated: 2020-12-26
Packaged: 2021-03-11 03:27:31
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,170
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/28328241
Author URL: https://archiveofourown.org/users/Kiramochis/pseuds/Kiramochis
Summary: The strange object that Lady Fate had guided Ryu to by her own hand turned out to be exactly what he was longing for. A mermaid. A real life mermaid had somehow gotten themselves beached right in Ryu’s own backyard.
Relationships: Izumi Mitsuki/Tsunashi Ryuunosuke
Kudos: 3





	The Lunar Mermaid

**Author's Note:**

> Merry Christmas and Happy Holidays! Written as a Secret Santa gift for keiure on Twitter

From a very young age, Ryu had always been told to be careful of the mermaids that live deep in the waters of his backyard. The elders in town would explain how the merfolk had a disdain for mankind, and would waste no opportunity to pull them down to a watery grave. While the reasoning was never told, the mermaids were often used as scapegoats whenever the fishermen came home with no stock, and as explanations for when ships were lost to sea. As he and his friends grew older, Ryu found himself being the only one who still believed in the tales told to him as a child. His friends teased him countlessly for his childish beliefs, but Ryu was determined to prove them wrong.

Summer lasted forever in his seaside town, so Ryu was out day and night trying to find some sort of proof of the illusive merfolk that lived deep below the currents. A single scale would never be enough, no matter what strange color it took, there was bound to be a fish in the area with the same colored scales. What he needed was an actual sighting. It would be alright if the mermaid never went up to the banks for everyone to see, the only person Ryu had to convince was himself. Even if the world was against him, as long as Ryu knew the truth, nothing could break his resolve.

Most of the time Ryu spent his time with his father on his fishing boat, working out at sea from dawn till dusk, but every day that he had off he was out riding the waves just behind his home. It started as a friendly outing with his friends to relax and unwind, but over time Ryu used it to his help further his goal. Unlike on his father’s fishing boat, when on a surfboard Ryu was much closer to the water.

One morning, when the fog was especially thick, Ryu had found the most unbelievable sight.

Ryu may be kind of dumb, but he isn’t stupid; he knew that going out to sea with such a heavy fog was not a wise idea. However, something had caught his eye when he went down to the beach to figure out how thick the fog was. A sparkle of orange reflected off of the light from the lighthouse not far from where he stood. Thinking it was a beached fish, Ryu slowly walked to the shiny object. If it was a fish and was still alive, he would throw it back into the ocean. If not, he would see if the fish was known to be poisonous before deciding if he would prepare it for dinner that night. If it turned out to be a human, Ryu would either call the authorities or an ambulance depending on how (or if) they were breathing.

Unfortunately (or maybe fortunately) it turned out to be neither, yet both at the same time.

The strange object that Lady Fate had guided Ryu to by her own hand turned out to be exactly what he was longing for. A mermaid. A real life mermaid had somehow gotten themselves beached right in Ryu’s own backyard.

The fog obscured most of their physical appearance, but the mermaid themself was smaller than what his grandmother had told him. She said that on average they were as big as a whale, while some of her friends told him that they could get even bigger than that. This one seemed to be smaller than Ryu. Their scales were a dark shade of orange, so dark in fact it was almost brown. The scales perfectly faded into skin that was just a few shades lighter. What had caught Ryu off guard the most was their short, vibrant orange hair. It almost seemed like a wig.

The wonder at the discovery soon settled into panic at the mythical creature’s wellbeing, Ryu placed his index and middle finger to the back of the creature’s jaw. There was a faint pulse. 

Now that he knew that the mermaid was still alive, more panic flooded in. Should he throw them back into the ocean or was that dangerous? There was no way they would survive in the freshwater his bathtub provided. There was, however, a small little spring filled with saltwater closer to his house that should be big enough to hold them until they regained consciousness. It was sheltered right beneath the back patio and had lattice fencing to cover up the rocks underneath that would provide them perfect shelter. There were holes in it of course, but luckily Ryu had a small door added onto the side so he could come in and out to keep it clean and to help get out any stray cats that managed to squeeze through one of the holes in order to take shelter.

As gently as he could, Ryu picked up the mermaid and raced back home.

*-*-*

Ryu had stayed underneath the patio for a while after he had brought the mermaid to the spring. It was deep enough for them to lay down in, but not enough for them to live there. Ryu had briefly checked for injuries when he had settled in, and thankfully there were no external injuries. During his quick checkup, Ryu also spotted some more of the creature’s defining features. Human ears where no were to be found, and in the spot where a pair normally would be sat a set of three pronged fins. Their hands were completely webbed, almost as if they didn’t actually possess fingers at all. 

“What on Earth am I going to do with you?” Ryu stared down into the small pool. The mermaid hadn’t moved a muscle since Ryu had laid him down a few hours ago. Maybe they had passed when Ryu wasn’t paying attention?

Ryu gently leaned over into the pool to check the mermaid’s heartbeat. With hands barely ghosting over the base of the mermaid’s jaw, the creature’s eyes snapped open. Before Ryu could tumble back from shock, the mermaid grabbed hold of Ryu’s arm and attempted to pull him under. They were unsuccessful however, since they were still weak after whatever event had caused them to beach.

Ryu was able to shake his arm free from the mermaid’s less than stellar grip. He sat up and looked at the glaring mermaid before him. Unlike human eyes, the mermaid’s eyes were completely orange, in the same vibrant shade as their hair. Orange seemed to be a running color scheme for them.

“Are you alright, you’re not hurt are you?” Ryu gently moved closer to the mermaid who only recoiled and made a noise somewhat reminiscent of a hiss at the motion. Ryu quickly pulled his arm back. 

“My name’s Ryu, I don’t want to hurt you.” The mermaid didn’t respond. “Are you well enough to return home? I can carry you back to the ocean if you’d like!”

When the striking glare being sent his way didn’t soften a little at the notion of returning home, Ryu figured the mermaid couldn’t understand him. Of course they couldn’t, that would have been too easy for him.

Ryu sighed to himself. “Well, I can’t just leave you here. You’ll die in a pool this small.” Attempting to pick them up would only result in grave injuries, but it was a risk Ryu was willing to take. He would rather himself get hurt than the mermaid die.

As gently as he could, Ryu grew closer to the mermaid. They hissed and recoiled like before, but Ryu didn’t pull back this time. With the gentleness of a fawn, Ryu brought one arm underneath their tail and the other went to support their back.

“Don’t worry, I’m taking you home now.” The mermaid didn’t know what to do at this point, and probably figured that Ryu wasn’t going to harm him. Ryu still sent them a gentle and reaffirming smile, hoping that maybe that would ease a little bit of their worries.

Ryu gently pushed open the door to the nook, careful to not let it swing back and hit them. 

The walk down to the beach was a short one. Much to Ryu’s surprise, the mermaid didn’t struggle at all. Ryu walked onto a small elevated collection of rocks not far from the shoreline. When Ryu and his friends go swimming, they usually jump off of this cliff. It wasn’t very deep, reaching up to Ryu’s waist when standing up straight but it should be deep enough to drop off the mermaid. 

Ryu gently kneeled down on the edge of the rocky cliff. Should he just drop the mermaid in? Set them down on the edge and let them return on their own? Before he could even make a decision, the mermaid seemed to have finally pieced together what was going on and jumped out of Ryu’s arms and into the cool ocean once more.

The mermaid popped their head out of the water, looking at Ryu with wide, orange eyes. Ryu gave them a shy wave of goodbye. Like a mime, the mermaid mimicked the motion before diving back into the water. Ryu watched as the mermaid swam away. Once he could no longer see the fading dot of orange, Ryu got up and made his way back home. He had finally gotten what he had wanted after all, so why was he feeling so forlorn?

*-*-*

Weeks had passed since Ryu’s fateful encounter, and he still hadn’t been able to put a label on his emotions. He often found himself wondering about the mermaid. Were they doing okay? Was there any sort of negative side effects from being out of the ocean for so long? He hoped not. Ryu hoped the little mermaid was still alive and healthy, swimming free with their friends or family. A little part of him hoped that they would visit, that maybe the mermaid had taken a liking to him. Every morning Ryu would visit the spot he had found them, but he found no indication that they had visited. Maybe they lived too far away from his little beach.

Stormy nights were not usual for Ryu. He had long since grown used to the sounds of harsh rain against his windows, and there was something almost magical about lightning when you saw it from a distance. Yes, storms no longer concerned him, but the sound of something banging on his back door did.

Ryu had already begun to settle down for the night, dressed in his pajamas and had just finished brushing his teeth when something akin to a mixture of knocking and rapping sounded from his patio door. No one in their right mind would be out at this time of night in this weather, but Ryu decided to go and check. It could have been a stray cat. A very big stray cat.

“I’m coming, I’m coming.” Ryu spoke just loud enough for whatever was there to hear. Not like it really mattered, those words probably held no meaning to a cat.

Except, when Ryu had opened the door, he didn’t find a cat. It was the farthest thing from a cat.

Standing on his patio stood a wet, cold and very much human person. They stood at the entrance, hands rubbing their forearms to try to stay warm. The rain didn’t seem to bother them, seeming completely fine with being drenched from head to toe. There was something almost familiar about this person, but Ryu couldn’t quite put his finger on it. Ryu ushered the stranger inside anway, refusing to abandon someone who clearly needed shelter. 

“Stay right there a moment, I’ll go grab you some towels!”

The stranger nodded and Ryu raced off to the linen closet. When Ryu returned once more, he saw the stranger looking around at the kitchen, eyes wide and full of stars. It was almost cute.

“Here you are.” Ryu handed the towels to the stranger. He watched as they unfolded the towels and stared at them with the same adoration as they did the kitchen.

“Do you need some help?” The stranger nodded “Here, let me dry off your hair then. I should also probably get you something to wear too.”

Ryu guided them to a chair at the breakfast bar and began drying off the stranger’s bright orange hair. They hummed and leaned into Ryu’s gentle touch.

“Do you like that?” The stranger nodded. “What’s your name?” They didn’t respond. Come to think of it, they hadn’t said anything at all up to this point.

“Can you speak?” Ryu asked. The stranger shook their head no. “Can you write?” They once again shook their head. How peculiar.

“Can you give me a hint about your name then?” The stranger tilted their head before standing up and began walking around the house. Ryu followed them. They stopped right in front of a pair of metal sun and moon decorations hanging in the entryway to the house. They pointed to the moon.

“Your name is Moon?” The stranger shook their head no, a bright smile on their face. They probably thought this was all amusing. So if it wasn’t Moon, then it had to do something with the moon. Ryu tried to recall all of the names he knew that had something to do with the moon.

“Is it, Apollo?” The stranger shook their head. “What about Callisto?” Again a no. Ryu went through a couple more names, some more obviously mood related while others seemed a bit more obscure. All of them were wrong.

“Is your name Mitsuki?” A nod of the head, almost enthusiastically so. “Well, it’s nice to meet you Mitsuki. My name is Ryu.”

Mitsuki smiled brightly, his teeth almost blinding. Ryu smiled back. “Let’s get you all dry. You can stay here for the night, or until the storm passes. Sound good?” Mitsuki nodded. “Great!”

*-*-*

Mitsuki had spent the night inside the guest room. Ryu was hesitant to leave him on his own, but he had quickly come to terms that if anything happened while he was sleeping, it would be his fault.

The next morning Ryu found Mitsuki sitting at the breakfast bar, staring out the kitchen window, watching as the sunlight danced on the ocean’s waves. Ryu had lent Mitsuki one of his shirts for the night, but based on their size difference, it seemed more like a dress than a shirt. Was it cute? Yes, very much.

“Good morning.” Mitsuki jumped at Ryu’s morning greeting. He looked back at him and smiled. “Do you want a cup of coffee? I can make breakfast too.” Mitsuki tilted his head, a confused look on his face. “Do you prefer tea?” Mitsuki tilted his head the other way. Ryu was convinced he was as confused as Mitsuki was at this point. This morning was definitely going to be a long one.

Breakfast had gone by as smoothly as spoiled milk. Mitsuki didn’t seem to like any of the food Ryu had prepared for them. With Mitsuki being unable to speak or write, breakfast became a guessing game. A not so very fun one at that. He didn’t seem to care for fruit or anything oat based, nor did he like certain kinds of meat. He did however, love fish. When Ryu had mentioned it, Mitsuki’s eyes lit up.

After breakfast had finished, Ryu gave Mitsuki some of the clothes one of his younger brothers had left over the last time they visited. He seemed so fascinated with the clothes he had been given, but didn’t know how to put them on. Ryu and Mitsuki did a simple yes or no questionnaire, and Ryu learned a bit more about Mitsuki. He was 21 years old, had a younger sibling.

Ryu had come to realize that Mitsuki didn’t know how to use a utensil of any kind. He struggled to use a fork and knife, which was better than his attempts at using chopsticks at least. By the time they finished breakfast, it was almost noon, and Ryu was starting to wonder if Mitsuki really was human after all. Being unable to speak was the least of his problems, or concerns at this point.

Mitsuki was currently sitting on the couch in Ryu’s living room, staring brightly at the TV. 

“Mitsuki?” He looked over at Ryu. “Can I ask you something?” Mitsuki nodded.

Ryu took a deep breath and sat down next to Mitsuki on the couch. “Do you have a home to go back to?” Mitsuki slowly nodded his head.

“Do you want to go home?” Mitsuki looked down at the floor and shook his head.

“Did your parents kick you out?” Again, a shake of the head. Simple yes or no answers wasn’t going to get Ryu the answers he needed. If Mitsuki hadn’t been kicked out, then why didn’t he want to return home?

“Can you go home?” Mitsuki shook his head no again. He looked over at Ryu, a worried look on his face. He probably thought that Ryu was going to kick him out. As if Ryu could do that.

“Hey, don’t worry. I’m not going to kick you out.” Mitsuki looked elated. “But if you’re going to stay you have to help out around the house alright?” Mitsuki nodded happily.

After a brief discussion about Ryu’s work schedule with his father, dividing up the chores between the two of them and assigning who would make dinner on what day Ryu had decided to take Mitsuki out to get some new clothes. He couldn’t keep wearing his brother’s clothes now could he? Plus he would have to get Mitsuki some children’s books to teach him how to read and write to make communicating more easier.

Ryu had left Mitsuki in the living room to go and get ready to leave, and when he was all set to go, he found Mitsuki leaning over the edge of the patio, looking at the ocean. Something had splashed into the water, but Ryu couldn’t get a good look at it and once again focused on Mitsuki.

“Are you ready to go?” Mitsuki jumped and looked back at Ryu. He nodded, but took one look at the ocean again. “Is there something out there?” Mitsuki shook his head. “Then let’s go. We can order out for lunch, how does that sound?” Mitsuki smiled and nodded. It was clear that the smile didn’t reach his eyes, but Ryu didn’t want to press into it.

With their backs turned, both of the young men missed a figure popping out of the water, one with hair as black as night and eyes a deep shade of navy. They let out a forlorn sigh for the lost member of their colony before diving back down and rejoining the group.

If Mitsuki was going to be happiest living with the human he had fallen in love with, then who was Iori to stop him?

**Author's Note:**

> My love of vaguely monsterish mermaids really came through with this
> 
> I didn't even read the rest of the prompts I was given, I just saw RyuMitsu and immediately went to work. I've wanted to write for RyuMitsu for so long you have no idea
> 
> I have a whole lot of lore about Mermaids that I would have loved to explore here, but if I where to go down that path this would never be released on time, so I'll put them in the end notes instead!
> 
> So basically Mermaids can be divided into two main categories: Freshwater and Saltwater mermaids. Freshwater Mermaids are your typical Disney Mermaids, a very clear distention between fish and human, have Human like sizes and speak Human languages. Saltwater Mermaids have less of a distinction between fish and human, do not speak Human languages, live in groups called Colonies and size depends on how deep in the ocean they live (the deeper they get, the less human they look too). Mitsuki's colony live closer to the surface so he and his family have more Human based sizes.
> 
> Scream with me on [Twitter](https://twitter.com/kiramochis/) about Mermaids


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